There are many applications in which it would be advantageous to provide non-planar integrated circuitry. For example, an optical imager requires large, heavy and complex optics if a wide field-of-view (FOV) image is to be projected onto a planar array of photodetectors. Being able to curve the photodetector array into a desired shape would simplify the optics required and substantially improve the imager's optical performance.
However, non-planar electronics are difficult to manufacture, and generally suffer from reduced performance when compared with state-of-the-art CMOS electronics, for example. Organic substrates are commonly used to provide flexible electronics, but organic substrate-based circuits typically provide a lower density of active circuitry, and are limited to operating at lower frequencies when compared with CMOS.
Another approach involves dividing a circuit into a number of adjacent segments which are foldable along their borders; one example is the 3-Die μZ™ Folded Die Stack from Tessera, Inc. However, this technique tends to accommodate a limited number of segments, and requires large dimension interconnections between segments.